Manufacture of artificial thread



Oct. 18, 1938. H. H. PARKER 2,133,714

MANUFACTURE OF ARTIFICIAL THREAD Filed June 19, 1953 Card electric furnace an, Scott 7295:67 to eguz'librzum ffimzn w,0 to 90 6 0 Cotton Cord rat r [ffect of 7am Air Temperature (6) WWQ fiwyw ATTORNEY Patented Oct. 18, 1938 UNITED STATES PATENT OFFICE Harold Henry Parker, Kenmore, N. Y., assignor,

by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application June 19, 1933, Serial No. 676,463

23 Claims.

This invention relates to the manufacture of artificial threads, horsehair, straw, films and the like, and particularly to the manufacture of viscose rayon threads. Specifically, the invention relates to the manufacture of artificial threads produced from viscose and characterized by unusual strength and elasticity and approaching and even surpassing the strength and elasticity of Egyptian Sak cotton.

In the normal operation of viscose rayon plants, the viscose is filtered several times in the ripening room. The viscose is then led through iron pipes to the spinning machine. In order to remove from the viscose, just before it passes through the spinneret, particles of dirt, scale,

etc. which are picked up after the last filtration, a filtering device called a candle filter is placed directly back of the spinneret. The usual candle filter removes dirt and scale fairly efiectively, so that the spinneret orifices do not tend to clog immediately due to dirt of this type.

In order to produce very high tenacity yarn, particularly in a non-plasticizing bath, it is necessary to apply a very high tension to the freshly formed thread, but ordinary viscose will not permit the continuous application of very high tensions.

I have found that by filtering the viscose and then conducting it through equipment which is non-corrosive, such as nickel pipes, to the spinning orifices, I am able to apply this very high tension to a thread freshly formedtherefrom without causing irregular spinning, i. e. frequent interruptions, and poor grading due to broken filaments. Utilizing-this principle, I have developed an orderly tension-spinning process substantially free from irregular spinning, and by which it is possible to spin at a very high tension and very much nearer to the breaking tension than has heretofore been the practice and produce a thread of good grading and also having the properties hereafter set forth.

More particularly, I have found that by spinning a viscose solution, such as described here- 5 inafter, in a process which preferably includes the development of a relatively high tension in stages in the thread, and preferably by means imposing a constant tension and free of sliding friction through a relatively long bath travel, I can produce a yarn characterized by unusual strength and high elasticity, particularly in the dry state, by virtue of which it is exceedingly well suited for the production of cords, fabrics, etc.

For instance, it is possible to spin at a tension very much nearer to the breaking tension than erally speaking, by bringing to the extruding device an improved viscose. In one embodiment, I produce the viscose by using such raw materialsand apparatus and such procedure as will 15 not cause the resulting viscose to be contaminated with undesirable impurities. According to this procedure, after ripening, the viscose is conducted to the extruding device through equipment made of a material which will not be corroded by the 20 viscose, will not contaminate the viscose, and will not promote the gelation of theviscose.

I have found that the quality of the viscose is most seriously affected in its passage, after leaving the relatively large and cool containers 25 of the ripenin room, in the warm spinning room, through iron pipes that have a large surface area as compared with the volume of viscose therein. I have found that, if I suitably filter the ordinary viscose and then deliver it to the extruding 30 device without change in quality, the viscose will permit attainment of the objects of my invention.

This viscose is one that is capable of being spun in an orderly manner, i. e. continuously for a 35 long period of time into a thread, under a total tension of at least or even of the ten-.. sion which will cause the thread to break during spinning, this breaking tension being not less than 1 gram per denier where the spinning proc- 40 ess is carried out as described in the following paragraph.

The viscose solution is spun through a -hole nozzle, each orifice being 0.0035 inch in diameter, to form a thread having a final denier of 275 45 in a coagulating-bath containing 9% sulphuric acid, 19% sodium sulphate, 1% zinc sulphate and. 4% glucose, at a temperature of 45" C. The thread travels 120 inches in the bath, during which time tension is gradually applied by means 50 of a plurality of roller guides, such as are referred to hereinafter, and then is wound up on a bobbin at 3000 inches per minute.

In one embodiment, my invention contemplates the filtration of the viscose near the spinning 55 signed to have the viscose in contact therewith for a minimum time and one made of materials as resistant as possible.

It is obvious, of course, that instead of nickel lines or equipment I may use equipment made of any material which will not be corroded by the viscose, will not contaminate the viscose, and will not promote the gelation of the viscose. For example, I can conveniently use equipment made of materials such as glass, rubber, alkali-resist ing molded compositions, or the commercial alloys known as Illium.- It is to be'und'erstood' that the aforementioned materials may be used singly throughout the entire equipment, or different parts ofthe equipment may be made of the various materials mentioned.

When the viscose solution, prepared and fed as above indicated, is spun, .a relatively high tension may be'applied to or developed in the filaments if a relatively long bath travel, such as greater than 20 inches, for example 45, 60, and

even up to 120 inches, or indeed up to 300 inches, or more, is used. Preferably, the tension which is imposed on the thread is constant and substantially free from sliding friction. As one 11- lustrative constant tension-applying means which may be employed in the invention may be mentioned rollers provided with means for develop ing a resistance to rotation in the bath, such as is particularly described in the copending application of Bradshaw and Hoif, Serial No. 303,574, and in Patent No. 1,878,455 of Banigan. Higher tensions may be applied'when the tension is developed progressively. For example, a thread may be conducted from the nozzle approximately 20 inches to a roller of the type previously described, and then back and forth'through the bath around a plurality, such as from 6 to 10, more or less, of successive rollers spaced from each other to give the thread the desired bath travel, and finally to the take-up device. It is to be understood that other guides may be used in combination with the guides aforementioned.

The total tension which is developed in the freshly-formed thread during the spinning operation may be in excess of 0.4 gram per denier, and preferably 0.5, 0.6, 0.7, 0.8, 1.0, or indeed more grams per denier. It is to be understood that when I speak of total spinning tension, I mean the tension on the thread between the last tension-applying device in the bath and the traverse guide (in the case of bobbin spinning) which lays the thread on the bobbin or (in the case of bucket spinning) the feed wheel.

Optimum physical characteristics of the thread are secured when a viscose having a salt index of between 3.4 and 4.9, and preferably approximately 4.0, is employed. Throughout this application reference to viscose salt index refers to those values determined by the process discussed on page 68, paragraph 2, of Artificial Silk by Reinthaler-Rowe, published in 1928.

In order to more fully explain the instant invention, there are hereinafter set forth several examples of the methods of operation which have given satisfactory results. It is to be understood that the invention is not restricted to these precise methods which are merely set forth for illustrative purposes.

Example I.-A viscose solution having a viscosity of approximately 4900 centipoises is prepared in the customary manner from a raw material containing a very high percentage of I alpha cellulose, for example cotton linters, in an equipment of the type previously described. After the solution is filtered and ripened to a salt index of approximately 4.0 it i'sfiltered in a nickel filter press and fed to the spinneret in a spinning machine through equipment, such as mani-- folds, connections, goosenecks, etc., on the spinning'machine, constructed of a material, such as nickel or its equivalent, which will not become corroded by the viscose nor contaminate the viscose. The thread is spun into a bath containing, for example, 9% sulphuric acid, 19% sodium sulphate, 1% zinc sulphate, and 4% glucose, at a temperature of "45 C., and wound up at 3000 inches per minute on a bobbin. Tension is ap plied to the thread in stages throughout a bath travel of'120 inches by means of a plurality of tension guides disposed at any suitable distance from each other and designed to impose tensions on the thread without substantial sliding friction on the thread. The total tension developed is approximately 0.76 gram per denier. The number of tension devices may, of course, vary. Subsequently, the thread is washed with water, to free it from acids, salts, etc., and dried. With or without subjecting the thread to further purification, it is passed through the usual textile operations.

Yarn produced by the foregoing process has the following physicals:

Range of Average value values Denier 275 Filament 120 Spinning tension, grams- 210 Spinning tension, g. p. (1.-.. 0. 76 Dry tenacity, g. p. d..- 3 09 2. -3. 40, Dry elongation, percent ll 0 6. 0-14 0 Wet tenacity, g. p. d.-- 1 72 1. 451. 87 Wet elongation, percent.-- I 16.2 10.0-21 0 Iodine test Reddish brown Cross-section Internal tension measurements" l8. 0% Dye index'" 12. 0 Elastic recovery"" 66. 0%

example a few loose threads, are immersed for 10 minutes in a solution containing 0.1 gram of iodine and 2.0 grams of potassium iodide in cc. of water. They are removed and the color noted.

'"The procedure here is as follows: The yarn to be tested is dried to bone dryness. It is then immersed in 119% aqueous caustic soda solution and the per cent shrinkage determined.

"Dye index figures represent shades in dyeing depth, the higher the number, the deeper the shade.

"To measure the elastic recovery, the thread is stretched 1nstantly 2%, held stretched for 100 seconds, and then allowed to recover for one minute and measured.

The method I use to determine tenacity and elongation and on which the above figures and those which follow are based is as follows:

The thread is reeled under uniform tension into 450 meter skeins. These skeins are conditioned for 3 hours in an atmosphere maintained at 60% R. H. and 75 F. The skeins are then weighed to determine the denier which is defined as the weight in grams of 9000 meters.

The breaks to determine tenacity and elongation are made on a Suter single strand strength and elasticity tester with an oil plunger controlled pull. The rate of fall of the plunger is 1 ft. per minute, and the distance between the clamps is adjusted for an 18 inch length of yarn.

In making the dry test, 5 single strands are selected from each of the above skeins. These are clamped in the tester separately and stretched dividing the scale reading in grams by the denier of the thread.

elongation up to 16.0%, a wet tenacity up to I." g. p. d., and a wet elongation up to 22.5%, has been secured. As additional illustrative examples of yarn produced by this procedure and having exceedingly high tenacities and elongations, the following values, representing tests on thread of high quality that is free from broken filaments and flufl,-'are given:

The average of 50 dry and 50 wet breaks on Dry Wet threads selected at random is considered to be D l the tensile strength for any given 100 pound lot er Elon El n aof yarn. Tenwty tio Temclty tier? Example II.Same as Example 1, except that the spinning bath contains 10.7% sulphuric acid a p, .1, m; u a. Percent and 23.5% sodium sulphate, and is free from 3-3; :32 g g glucose and zinc sulphate. 1 1510 1174 2215 Yarn produced by the foregoing process has ig-g 3-2 t e following Physicals! 2199 1510 1:68 20:5 22.? lit 1%; e2 Range of 3101 1510 1112 2210 Averag value values 3.00 15. o 1.68 22.0 a. is 12.2 2( 8 s. 12 1. :g i 75 3. 12 16. 1. 69 19- 5 lament 120 Spinning tensionfgramsm 210 gpinltiing t%nsion,gap.d Similar results may be obtained by treating ry enacl y, g. p. Dry elonization'DmenLflfl u the thread with solutions, such as alkali, alcohol, lzreitcttlanacitty, g. p. d; t 1.70 or in general, any agents which have a tendency Ioin e t e t gtg to swell the thread. The operation may ob- ICrgasssection. I Highly crenul ated surface viously be carried out as desired with either hot lfiluemfitis inffffi 20.0% or l solutions- Y gm Example V.-The mode of procedure is the as w 6 same as in Example II, except that a bucket ma- Determined as in first table of physicals.

tions. The physical properties of this yarn are as follows:

Range of Average value values Denier 275 Filament 1Z0 Spinning tension, grams 262 25()270 Spinning tension, g. p. d 0.95 0.93-0.97 'Dry tenacity, g. p. d 3. 24 2. 98-3. 40 Dry elongation, percent 7.0 5. 5-8.0 Wet tenacity, g, p. dl. 82 Wet elongation, percent-.. 11. 4 Iodine test Reddish brown Cross-section Highly crenulated surface Internal tension release 7 measurements"... 22. 0% Dye index' 11.0% Elastic recovery'' "l 63. 0%

*, "t t" Determined as in first table of physicals.

Exam le lV.The method of operating is the same askfor Example I, except that the thread, after drying and twisting, is reeled into skins, which are then wet with water and dried under no tension. The thread so obtained has a denier. of 286, an average dry strength of 2.93 g. p. d., with dry elongation of 14.6%, and an average wet strength of 1.65 g, p. d., with wet elongation of 19.0%.

It is to be understood that this procedure depending on the characteristics of the yarn as spun will produce yarn having higher tenacities and elongations than those set forth. Yarn having exceedingly high tenacities and elongations, such as a dry tenacity up to. 3.12 g. p. d., a dry chine is used in place of the bobbin machine. In thismodification, the thread is conducted around the feed wheel with the aid of auxiliary rollers, if desired, two or more times to prevent slippage, and is then drawn through a traversing funnel in the customary manner into a revolving bucket and collected in the form of a cake.

Since the tension on the thread, after it leaves the feed wheel, is governed mainly by the censpinning this yarn in the bucket process has a.

very favorable influence on the physical characteristics of the thread. 'Elongat-ions are appreciably increased due'tO this release of tension when the thread is in a very plastic condition. It will also be realized that the release of tension results in greater ease of washing and makes the process more practical from a commercial standpoint. M

This modification of the process has the further advantage that the yarn is given a twist during the spinning operation. This is advan tageous in that the twisting of the yarn at this point tends to make the subsequent handling easier and tends to make it easier to produce the yarn free from flufi and looped filaments. The yarn produced by this modification of the process has about 1% higher average dry elongation andabout 2% higher average wet elongation than yarn produced by the bobbin process previously described. i

In general, the thread of my invention is characterized by an average dry tenacity of not less than 2.9 grams per denier, such as 2.95, 3.0, 3.1, 3.2, 3.4 grams per denier, or more, and a high elongation relative to its tenacity. In copending 5 application of Bradshaw and Hoff, Serial No.

655,738, a thread having a relatively high elongation for a given tenacity is defined as one which possesses at least and usually or even or more, higher elongation than the elon l0 gation of a thread having the same tenacity, but

which in spinning has been tensioned through the application of' substantial sliding friction. Through the use of my improved viscose, I am able not only to maintain this high elongation 15 relative to the tenacity, as set forth by Bradshaw 20 both threads is the same have markedly different elongations. In one case, when the thread is tensioned by means of frictional guides, such as a series of stationary glass rods over which the thread slides, so that the final dry tenacity is 2.9 g. p. d., the dry elongation is 6.8%, whereas in the other case where the thread is tensioned by means of rollers, so that frictional resistance is substantially eliminated and so that the final dry tenacity is the same, the elongation is 9.4%. Thus, we see an improvement in elongation amounting to 38%.

It is difficult to make a direct comparison with the application of Bradshaw and Hofi, because they did not produce threads in my preferred 1 tenacity range. I can, however, point to a Bradshaw and Hofi thread (one tension-spun by means of roller guides and without substantial sliding friction) that has 'a dry tenacity of 2.73 g. p. d. and a dry elongation of 8.3%; that is com- 40 parable, in view of its method of preparation, to

the tenacities are markedly different.

' a thread spun from my improved viscose which has a dry tenacity of 3.06 g. p. d. and a dry elongation of 8.0%. It is readily seen that the elongations are not substantially different, but that Normally, an increase in tenacity such as shown here is accompanied by a much lower elongation.

When I spin my high quality viscose'according to the Bradshaw and Hoff invention at lower o tensions to produce a thread having a dry tenacity of 2.75 g. p. d., I find that the dry elongation of this thread is 12.2%. This is a substantial improvement over the thread obtained with normal viscose which with the same tenacity has an elon- 55 gation of 9.7%.

The thread has a very highelasticity, at least ,equal to that of high grade cotton thread of equivalent size, such as thread of high grade Egyptian Sak cotton which is used for high quality, heavy duty tires.

Typical physical properties of high grade Egyptian Sak cotton are as follows:

(b 0) Determined asin first table of physicals.

The thread of this invention possesses an unusual-resistance to the loss of strength with increasing temperature. This is well illustrated by I the data shown graphically in the figure. Referring to the graph illustrated in the figure, it will be noted that a cord, formed of rayon described in this applicatiomand having a lower strength than a cotton cord at room temperature, retains this strength, so that at all temperatures about 52 C. the rayon cord is actually stronger. The rayon cord and the cotton cord have the same diameters, but the weight per unit length of the rayon cord is approximately 15% higher than the cotton cord, since the rayon has a more compact structure.

The rayon cord is prepared as follows:

Five unit threads (275 denier-120 filament), each having a strength of 2.96 grams per denier and each twisted ,to 7 turns per inch, are combined by twisting on a ring twister to 20 turns per inch in the direction opposite to the twist of the individual thread to produce a strand. Three of these strands are united by twisting in the reverse direction to 10 turns per inch.

The cotton cord is similarly prepared. Five threads of 23 count cotton (each of said threads being equivalent to about 231 denier, containing 20 turns per inch of twist and having a gram per denier strength of about-2.2) are combined with twisting on a ring twister to 20 turns per inch, the twist being in a direction opposite to the twist in the individual threads to produce a strand. Three of these strands are then combined by twils lting in the opposite direction to 10 turns per mc It is to be noted that the cotton cord has a gram per denier strength of 2.15 as compared with the cotton thread strength of 2.2 grams per denier. The gram per denier strength of the rayon cord is approximately 1.7, whereas the corresponding rayon thread has a strength of about 2.9 grams per denier.

the rayon of the instant invention retain its strength with increasing temperature to a greater degree than does cotton, but also, when aged at these higher temperatures, it resists much better than cotton the degrading effect of heat which results in permanent loss oi. strength. For example, in a laboratory aging testconducted at 160 C., the rayon thread loses strength only half as rapidly as a comparable cotton thread. These laboratory tests, showing the increased resistance of my thread to heating, have been confirmed in service tests with such products as steam hose. Thus, it has been definitely shown that this characteristic property of the thread described in this application makes it of a particular value for such uses as heavy duty tires, steam hose, or in fact in any use where heating with the resultant degradation at high temperature is an important factor in durability.

The cross-section of the filaments of the thread of this invention is very highly crenulated, and, because of this, it possesses great covering power and filling power and is less apt to slip in the fabric than smooth surfaced yarn when the yarn is used in the customary textile operations.

The yarn is further characterized by an outer wall structure when viewed in cross-section under a microscope under the conditions hereafter set forth. This characteristic is not found in high tenacity yarn spun in plasticizing baths, such as containing or more, of sulphuric acid, and

in this respect plasticized, regenerated cellulose threads prepared from viscose are more like cu- .40 My tests have further shown that not only does prammonium cellulose threads which are also without this characteristic wall structure.

In order to view this characteristic structure,

filament cross-sections are prepared as follows:

Cross-sections of the threads are cut from the customary paraffin block, wherein they are mounted in the usual manner, and the paraflin is removed from the cut filaments by means of a suitable solvent. The filament cross-sections are mounted ona slide, wet with a drop of water, and then covered with the usual cover glass. Under the miscroscope, the characteristic wall structure just mentioned is readily discernible.

The high strength of this thread, together with the crenulated surface of the filaments, the high resistance to heat, and the freedom of the thread from broken filaments, makes the thread admirably suited for the manufacture of cords or fabrics for use in vehicle tires, steam hose and belts, of balloon cloth, re-enforcing fabrics, brake linings, filter cloths for hydraulic presses, parachute cloth, electrical insulation, aeroplane cloth, fabric for use in highway construction, etc.

Another important result which can be seccured by the use of my viscose made in accordance with this invention is the spinning of a high tenacity, high denier and high filament count thread of good grading, i. e. freedom from broken filaments. As will become apparent fromthe illustrative specific examples herebefore set forth, a 2'75 denier-120-filament thread having a tenacity in excess of 2 grams per denier, such as 2.96, 3.0, 3.1, 3.2, 3.3, 3.4 grams per denier, or more, and of good grading can be spun. This, of itself, is a surprising and marvelous achievement when it is considered that it takes very little, such as the partial plugging of one or more holes of the spinneret, to give a final product of poor grading. Formerly, it was necessary, in order to produce threads of high denier, to spin light weight threads and then double them in succeeding textile operations. It is to be understood that the invention can be used in the production of high denier, high filament thread other than that set forth above, such as a 200 denier-80 filament thread, a 350 denier-140 filament thread, a 275 denier-200 filament thread, a 200 denier-200 filament thread, etc.

' As the spinning tension increases and as the number of filaments increases and the denier of the thread increases, it becomes increasingly difficult to produce threads of good grading. In my early work on the spinning of high denier, fine filament thread, I was unable to produce threads possessing the hightenacitiesset forth hereinbefore and, furthermore, these threads were of exceedingly poor grading, containing, for instance, upwards of 200 or even 300 broken filaments in a 3000 yard skein of 275 denier-120 filament thread. On the other hand, with my improved viscose, I am able to produce a 275 denier- 120 filament thread that has less than 50 broken filaments per 3000 yard skein and, in general, no more than 10 broken filaments, or as few as 5 broken'filaments, or even less.

Exceedingly fine filament threads, such as 100 denier-100 filament or other yarn of 1 denier per filament or less, have not generally been produced from viscose, not because such threads could not be spun, but because in spinning anv excessive number of filaments were broken and the final thread was without commercial value. While it was understood that the production of these very fine filament threads required unusually wellfiltered viscose, none of the ViSCO$e$ f the prior art was capable of producing the high grade fine filament threads that I secure through the use of my improved viscose. For instance, I may spin my viscose into 100 denier-100 filament thread of high grading at normal spinning tensions, i. e. below 0.4 g. p. d. or even as little as 0.3, 0.2 or 0.1 g. p. d. or less. In the production of this fine filament thread, the characteristics which permit me to apply excessively high tensions to the thread also enable me to spin extremely fine filaments at low tension without the breaking ordinarily encountered with ordinary viscose.

Whenthe yarn is to be used in the production of highly twisted cord, I prefer to spin the thread in a zinc-glucose-acid-sulphate bath. The cords prepared from thread so spun have higher elongation, higher normal strength, and higher hot strength than cords prepared from thread spun in an acid sulphate bath. All of these properties contribute to give the product prepared from these cords greater durability with resulting increase in service life.

Though, in the specific and preferred examples, the spinning bath is described as containing a concentration of acid which does not plasticize the thread, the invention is not restricted thereto. The principles of the instant invention are equally applicable to procedures employing spinning baths containing a concentration of acid which will plasticize the thread, such as, for example, not less than 50% of a mineral acid, such as sulphuric acid, and if incorporated in such a process, may be expected to contribute corresponding advantages and improvements.

In this specification and claims the expression spinning machine is intended to cover a machine which includes a plurality of spinning positions and a manifold, traversing the length of the machine, and which feeds the viscose to each spinning position.

In this specification and claims the expression quality or equivalent terminology, when used in connection with describing the viscose solution, is intended to cover'the composition, concentration, salt point, contamination (or freedom of impurities) of said viscose.

Though the specific embodiment of the invention has been described in connection with the manufacture of viscose'rayon, it is to be understood that the principles of the invention-apply equally as well to the production of such materials as sheets or films of regenerated cellulose, artificial horsehair, artificial straw, and the like.

Since it is obvious that various modifications may be made in the specific details above described, the invention is not restricted thereto except as defined in the appended claims.

I claim:

1. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a filter press formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution inadvance of a manifold of a'spinning machine, thereafter conducting said viscose solution to the manifold of the spinning machine and to the extruding device, and maintaining the quality of said viscose solution substantially the same during its passage after filtering by the filter press to the extruding device.

2. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filteringa viscose solution through a nickel filter press in advance of a manifold of a spinning machine, thereafter conducting said vis- I as cose solution to the manifold of the spinning machine and to the extruding device, and maintaining the quality of said viscose solution substantially the same during its passage after filtering by the filter press to the extruding device.

3. In a method of preparing artificial threads,

films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a filtering device formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution in advance of a spinning machine having a manifold formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution, and thereafter conducting said viscose solution to the manifold of the spinning machine through equipment which is not corroded by said viscose solution and does not contaminate said viscose solution.

4. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a filter press formed of a material which is not corroded by said viscose and does not contaminate'said viscose solution in advance of a spinning machine having a manifold formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution, and'thereafter conducting said viscose solution to the manifold of the spinning machine through equipment which is not corroded by said viscose solution and does not contaminate said viscose solution.

5. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a nickel filter press in advance of a spinning machine having a manifold formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution, and thereafter conducting said viscose solution to the manifold of the spinning machine through equipment which is not corroded by said viscose solution and does not contaminate said'viscose solution. g

6. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a filtering device formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution and in advance of a spinning machine having, a manifold formed of a material which is not corroded by said viscose solution and does not contaminate said vis" cose solution, and thereafter conducting said viscose solution to the manifold of the spinning machine and to the extruding device through equipment which is not corroded by said viscose solution and does not contaminate said viscose solution.

'7. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a filter pressfformed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution and in advance of a spinning machine having a manifold formed of a material which is not corroded by'said viscose solution and does not contaminate said vis-v cose solution, and thereafter conducting said viscose solution to the manifold of the spinning machine and to the extruding device through equipment which is not corroded by said viscose solution and does not contaminate said viscose solution.

8. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a nickel filter press in advance of a spinning machine having a manifold formed of a material which is not corroded "by said viscose solution and does not contaminate said viscose solution, and thereafter conducting said viscose solution to the manifold of the spinning machine and to the extruding device through equipment which is not corroded by said viscose solution and does not contaminate said viscose solution.

9. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a nickel filter press in advance of a spinning machine having a nickel manifold, and thereafter conducting said solution through nickel pipe lines to the said nickel manifold of the spinning machine.

10. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise filtering a viscose solution through a nickel filter press in advance of a spinning machine having a nickel manifold, and thereafter conducting said solution through nickel pipe lines to the said nickel manifold of the spinning machine and to the extruding device.

11. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise preparing a viscose solution having a salt index between 3.4 and 4.9 and capable of being spun in an orderly manner under a total tension of at least of the tension which will cause the thread to break during spinning, filtering the viscose solution through a nickel filter press in advance of a manifold of a spinning machine, thereafter conducting said viscose solution to the manifold of the spinning machine and to the extruding device, maintaining the quality of said viscose solution substantially the same during its passage after filtering by the filter press to the extruding device, and spin ning said viscose solution under a total tension of from 85% to of the tension which will cause said thread to break during spinning.

12. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise preparing a viscose solution having a salt index between 3.4 and 4.9 and capable of being spun in an orderly manner under a total tension of at least 85% of the tension which will cause the thread to break during spinning, filtering the viscose solution through a filtering device formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution and in advance of a' spinning machine having a manifold formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution, thereafter conducting said viscose solution to the manifold of the spinning machine through equipment which is not corroded by said viscose solution and does not contaminate said viscose solution, and spinning saidviscose solution under a total tension of from 85% to 90% of the tension which will cause said thread to break during spinning.

13. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise preparing a viscosesolution having a salt index between 3.4 and 4.9 and capable of being spun in an orderly manner under a total tension of at least 85% of the tension which will cause the thread to break during spinning, filterlng the viscose solution through a nickel filter press in advance of a spinning machine having a manifold formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution, thereafter conducting said viscose solution to the manifold of the spinning machine through equipment which is not corroded by said viscose solution and does not contaminate said viscose solution, and spinning said viscose solution under a total tension of from to of the tension which will cause said thread to break during spinning.

14. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise preparing a viscose solution havin a salt index between 3.4 and 4.9 and capable of being spun in an orderly manner under a total tension of at least 85% of the tension which will cause the thread to break during spinning, filtering the viscose solution through a nickel filter press in advance of a spinning machine having a manifold formed of a material which is not cor-- roded by said viscose solution and does not contaminate said viscose solution, thereafter conducting said viscose solution to the manifold of the spinning machine and to the extruding device through equipment which is not corroded by said viscose solution and does not contaminate said viscose solution, and spinning said viscose solution under a total tension of from 85% to 90% of the tension which will cause said thread to break during spinning,

15. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise preparing a viscose solution having a salt index between 3.4 and 4.9 and capable of being spun in an orderly manner under a total tension of at least 85% of the tension which will cause the thread to break during spinning, filtering the viscose solution through a filtering device formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution and in advance of a spinning machine having a nickel manifold, thereafter conducting said solution through nickel pipe lines to the said nickel manifold of the spinning machine, and spinning said viscose solution under a total tension of from 85% to 90% of the tension which will cause said thread to break during spinning.

16. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise preparing a viscose solution having a salt index between 3.4 and 4.9 and capable of being spun in an orderly manner under a total tension of at least 85% of the tension which will cause the thread to break during spinning, filtering the viscose solution through a nickel filter press in advance of a spinning machine having a nickel manifold, thereafter conducting said solution through nickel pipe lines to the said nickel manifold of the spinning machine, and spinning said viscose solution under a total tension of from 85% to 90% of the tension which will cause said thread to break during spinning.

17. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise preparing a viscose solution having a salt index between 3.4 and 4.9 and capable of being spun in an orderly manner under a total tension of at least 85% of the tension which will cause the thread to break during spinning, filtering the viscose solution through a nickel filter press in advance of a spinning machine having a nickel manifold, thereafter conducting said soluunder a total tension of from 85% to 90% of the tension which will cause said thread to break during spinning.

18. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which comprise preparing a viscose solution substantially free of deleterious contaminations,discharging the viscosesolution from the ripening room, and delivering it to a spinning machine manifold formed of a material which is not corroded by said viscose solution and doesnot contaminate said viscose solution through equipment which is not. corroded by said viscose solution and does not contaminate said viscose solution.

.19. In a method of preparing artificial threads, films, horsehair, straws, etc., the steps which coinprise preparing a viscose solution substantially free of deleterious contaminations, discharging the viscose solution from the ripening room, and

delivering it through a nickel pipe line to a nickel,

manifold of a spinning machine.

20. In an apparatus for preparing artificial threads, films, horsehair, straws, etc., by the viscose process, a spinning machine having a manifold formed of material which is not corroded by said viscose solution and does not contaminate said viscose solution, a filtering device formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution and in advance of the manifold of said spinning machine, and pipe lines to conduct the viscose from said filter press to the said manifold of the said spinning machine, said pipe lines be-' ing formed of a material which is not corroded by said viscose and does not contaminate said viscose.

21. In an apparatus for preparing artificial threads, films, horsehair, straws, etc., by the viscose process, a spinning machine having a manifold formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution, a filter press formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution and in advance of the manifold of said spinning machine, and pipe lines to conduct the viscose from said filter press to the said manifold of the said spinning machine, said pipe lines being formed of a material which is not corroded by said viscose and does not contaminate said Viscose.

22. In an apparatus for preparing artificial threads, films, horsehair, straws, etc., by the viscose process, a spinning machine having a manifold formed of a material which is not corroded by said viscose solution and does not contaminate said viscose solution, a nickel filter press in advance of the manifold of said spinning machine, andpipe lines to conduct the viscose from said filter press to the said manifold of the said spinning machine, said pipe lines being formed of a material which is not corroded by said viscose and does not contaminate said viscose.

.23. In an apparatus for preparing artificial threads, films, horsehair, straws, etc., by the Viscose process, a spinning machine having a nickel manifold, a nickel filter press in advance of said manifold of said spinning machine, and pipe lines to conduct the viscose from said filter press to the said manifold of said spinning machine, said pipe lines being formed of nickel.

HAROLD HENRY PARKER. 

